Drawbench



D. V. STROCK Aug. 19, 1952 DRAW BENCH 7 Sheets-Sheet 1 Filed April 15, 1946 k m m 5 V p M Aug. 19, 1952 D. v. STROCK DRAW BENCH '7 Sheets-Sheet 2 Filed April 15, 1946 INVENTOR. DONALD v. STPO-C/f BY 6917M die/(W A 770 ZEN/5Y5;

Aug. 19, 1952 D. v. smock DRAW BENCH 7 Sheet'S-Sheet 3 Filed April 15, 1946 INVENTOR. DONALD V STROCK ELM wwlw A TTOfP/VE Y5 Aug. 19, 1952 D. v. STRQCK DRAW BENCH 7 Sheets-Sheet 4 Filed April 15, 1946 llll'l'llv IN VEN TOR. .DONA L .D V- STEOC/T BY 6 M) A T TOFNEYS D. V. STROCK Aug. 19, 1952 DRAW BENCH [Sheets-Sheet 5 Filed April 15, 1946 INVENTOR. DONALD v. STEOC/f 7 BY maul- Wye/aw ATTORNEYS D. v. sTR'QcK Aug. 19, 1952 DRAW BENCH 7 Sheets-Sheet 6 Filed April 15, 1946 INVENTOR. DONALD V- 577F061? BY flaw \Ywl ATTORNEYS Aug. 19, 1952 D- v. s'rRQCK DRAW BENCH 7 Sheets-Sheet 7 Filed April 15, 1946 IIIIIIIIIII ,INVENTOR. DONALD v- STIEOC/F ATTOE/V'YS Patented Aug. 19, 1952 UNITED stares rerE Nr OFFICE acomti V a DItAWBEfiori Donald Strock, Youngstown; -hio; assignor to The e r and r ine r n Co Youngstown, Ohio, a corporation of Ohio Application April 15, 1946; serial No 662,126

aciaims. (01,205+?) This invention relates to draw benches of the type employed inthe manufacture of drawn tubes,- bars and the like. While: the invention willbe describedherein-with reference to a bench particularly adapted to the" drawing or tubes, it will be understood that it also is adapted to the manufactureof other articles that can be processed on adr-aw bench, and such articles are: intendedto be included: when reference is made herein to tubes. V

Conventionaldraw benches ordinarily comprise a bed upon which is mounted a traveling; car.- ri'ag'e provided with jaws to grip a'tube and draw it over a mandrel-supported by a mandrel rod, and through a forming die that is mounted at one end of the bed. At the conclusion of the drawing operation the drawing tubeis released and the carriage is returned to the die stand to grip the next tube that is to be drawn through the die, To increase the output of tubes, draw benches have: been built'with. a plurality of mandrel rods and cooperating dies so mounted that a tube to be drawn-maybe loaded on one" mandrel rod duringthe interval when another mandrel rod is in alignment with the die through which a tube previously loaded on the rod is being drawn.

Such a draw' bench is disclosed in Patent No. 2,196,155; issued April- 2, I940, the name of Howard W-.'Smith, and assigned to my assignee. The draw bench of the present invention embodies certain improvements over'that one disclosed in thesmith patent, particularly in that part of the draw bench commonly called the back bench. Such improvements have to do,'among other things, with the manner in which the mandrel rods are mounted and shifted to and from the loading and drawing positions;

Accordingly, a generalobjeet of the present invention is the provision of a draw bench of iniproved construction in which vone tube may be drawn over a mandrel; and through aadiewhile a second tube is'being loaded upon a mandrel rod preparatory tomovement-to the'position where it inturn may be drawn through the die. Another objector the invention is to provide an'impr'oved mechanism embodying at least twogmandrel' rod assemblies that may beshifsted; alternatelybetweena loading and drawing position while they are maintained paralleleach to eachand in horizontal positions. A further'object-is to {make provision for locking that assemblythatisin the drawing position positively to the draw bench frame and releasing it at the end of the drawing operation: Stillanother object of the invention 2 V is to provide improved and power operated mechanism' for shifting the mandrel rod assemblies between the loading and drawing positions. An additional object of the invention is to provide mechanism for shifting the mandrel rods from one-to another of two vertically aligned positions Withou't tilting the mandrel rod assemblies either lengthwise or transversely of the mandrel rod Another object is to provide fluid pressureaxes. mechanism for shifting the mandrel rod assemblies from one to another position and also for positively locking an assembly in one of such positions. A still further objectis to provide an improved mounting for a mandrel rod inthetrough of a mandrel rod assembly.

Further objects and advantages of the invention will become apparent fromthe following description of apreferred form thereof, reference being made to the accompanying drawings, The essential and novel, characteristics are summariZdiHthGClfiimS;

Referring now to the drawings: Figure 1 is a side elevation of a draw bench made according to apreferred formfl of the invention; Figure 2-is a fragmentary section on an enlarged scale and. in a: plane parallel to Figure 1, showingthe assembly adjacent the drawing die; Figure 3 .is' a section through Figure 1' as indicated by the lines 3-3 thereon; Figure lzis a. side. elevation at one end of the draw bench showing the mechanism for moving the r'nandrel rods towards or away from the die; Figure 5'is an incomplete section parallel to Figure; and indicated' by lines 51-5 in Figure 6,. showingtlime'c'hanism' by which the mandrel rods are locked in drawing position; Figure 6 is a transverse section as indicated by the lines 6-6 on- Figure 5; Figure- 7 is a fragmentary section parallel to Figure 6 showing in detail parts of the mechanism by which the mandrel rods are raised and lowered; Figure 8 is afragmentary plan view ofone of the mandrel rod assemblies showing three individual mandrel rods and their ing mechanism difiiering somewhat rromthat shown inFigu-re's' 6" and '7; .Figurezl'l is a detail section illustrating the driving mechanism Lfor shifting the mandrel rod assemblies; and Figure 12 is a detailshowing in cross section the construction of a mandrel rod trough and its supporting arm.

The general arrangement of a preferred form supported in guide troughs 35. rods, tubes and trough of a complete assembly are shown; it will be apparent that more or less than this number may be used if desired. The mandrel rod assemblies are moved back and forth between the loading position 22 and the drawing position 23, which positions preferably are in vertical alignment with each other, by rock arms best shown in Figures Hand '7 and described hereafter in detail. Tubes to be drawn are mounted on the mandrel rods by feed rollers .24 when the mandrel rods are in a position aligned with the l 'sothat the plugs are positioned closely adjacent the dies 25 in accordance .with customary practice. The rods are disposed in supporting tubes 34 (Figure 5) and these tubes. in turn are The mandrel 38' that support track members '40 and 4| on' which the carriage 20 travels back and forth.

The track members each constitute toothed rack bars that are engaged by power driven pinions carried by the carriage to move the same along the. track. This mechanism is shown and described in detail in copending application Serial No. 599,185, entitled Draw Bench, filed in the name of Glenn W. Garwig and assigned to the present assignee, now Patent No. 2,536,637, issued January. 2, 1951.

The beams that support the track members are themselves supported by large frame members 43 spaced along the bed as shown in Figure 1. These members are provided with base portions 44 that extend below the track to provide a generally C-shaped structure to lendstability to the assembly. The beam 3'! is supported as shown in Figure 3 by the generally vertical portion of the member and the beam 38 is supported in similar fashion from a downwardly extending portion 45 of the frame The loading rack l8 of the draw bench is -mounted on the flat tops of the members 43 as s'hownin Figure 3. Guide blocks 41 may be -mounted in the rack 18 to facilitate the alignment of the tubes as they are fed from the rack over the mandrel rods by the feed rollers 24 (Figure 2).

Tubes that have been drawn through the die '25 are discharged from the draw bench as shown level of the dies 25.

in Figure 3 through the space between the track members 40 and 41. Sloping guide rails 50 are provided on the frame members 43 to receive tubes falling upon them when they are released from the carriage and guide them to the open side of the bench Where they fall into a receiving trough 52.

The mandrel rod assemblies and the mechanism by which they are shifted are supported by a longitudinally extending frame that appears to 'the left of and in alignment with the bed 15 shown in Figure 1. This frame comprises an I-beam 53, one end of which is supported on and rigidly secured to a plate 54 secured tothe die stand I! (Figure 2) and the other end of which is secured'at 55 (Figure 5) to an end frame built up of structural sections welded together as shown.

The two mandrel rod assemblies are shifted from the upper loading position to the lower drawing position and back again by mechanism best shown in Figures 6 and '7. As stated above, these two positions are in Vertical alignment, and hence it is necessary to move one assembly down and out from the ,top position while the other member is moved up and out from the lower position in order that they may clear each other in passing. In the present embodiment of the invention three mandrel rods are provided in each assembly to permit three tubes to be drawn simultaneously through three dies 25. The assemblies are so shifted that the rods of each assembly maintain a substantially parallel position to therods of the other, assembly at all times, and-the rods of each assembly lie at all times in planes substantially parallel to the horizontal. The assemblies 7 are each raised and lowered by rock arms pivoted on axes parallel to the rods and supported by the frame below the As many complete sets of these rock arms may be spaced along the frame 53 as may be required accurately to support and .move, the mandrel rod assemblies.

a pair of spaced plates and H welded toa sleeve 13 keyedto a rock shaft (Figure 5).

The lower rock arm 65 is formed from a pair of.

plates 1'! and 18 welded to a sleeve '19 that in turn is keyed to a rock shaft 80. The plates of the lower rock arm are spaced inwardly of the plates of the upper rock arm (Figure 5)- so that the twoarms may interfit as they rock to their extreme positions (Figure 7). The outer ends of the shafts 15 and are journaled at 82'and 84 in a plate 85 that comprises part of the end frame of the draw bench (Figure 5), and at their other ends the shafts are mounted in bearings (not shown) that are similar to the bearings at 82 and 84 and are adjacent the beam support 55. The shafts that actuate the rocker arms are rotated in their bearings by the mechanism illus- 'trated in Figure 11.

As there shown an angle plate 81 fits into a channel of the beam 53 and is welded to it. Carried by the plate is a'subframe 88 that at one end supports a cylinder 89 sions.

and at the other and provides a sliding. bearing 80 for alpiston. rod 92 secured to a piston within .thez'cy'lind'er' 89;. The rod 91-2 isoperatiVeIy connected'. through a link 9 with a sprocket chain 95 that rides on sprockets 91 andild on the: shafts 1:5- and; 80 respectively. .As the piston: rod. 92 is reciprocated. in either direction by 'i-reason of .fluid pressure admitted to and; exhausted from the cylinder:&&,. it acts. to move the sprocket chain 95 and to rotate sprockets 91 and-9ft and: shafts i=5 and'Bfl through a. partial revolution. As the shafts are. rotated, they transmit a; correspond.- ing movement to the rocker arms 64 and 65 to shift. the mandrel. rod assemblies through. arouate paths between the loading and drawing positig The positions of the: assemblies. during their .movement is: indicated in solid. and dotted? lines fir-Figures: 6 and '7... When the parts are: in. the position". shown in Figure '7, that assembly supported by the bars 56 is in the upper: or loading position, and that assembly supported by the bars 5.! is in the lowered or drawing position. To reverse the relative positions of the assemblies, the shafts 1-5 and 80 arerocked in a counterclockwise direction by" actuating-- the: piston in the cylinder 89 (Figure 11).- This motion causes the upper assembly to travel downwardly and initially to the left as shown by the arrows in Figured, while the lower assembly-travels upwardly and initially to the right. Whenthe rock arms 64' and 65 aresubstantiallyhorizontal as shown by the dotted lines in Figure 6, the assemblies will have attained side bysi'deposit'i'on's. 'It will b'e evi'dent'i-romthis'figure that the motion imparted to the assemblies allows them to clear each other as 'the'one is lowered and the other is raised. Further counterclockwise movement of the shafts causes the left hand assembly in Figure 6'- to move downwardly and inwardlyuntil itsmand'rel rods are'i'n alignment with the individual dies and at the same time the right hand assembly moves upwardly and inwardly until its mandrel rods are'in alignment with the feed rolls 2 5 and the rack l-8-.'

A major advantage of thepresent invention arises from the fact 'that each assembly of mandrel rods, tubes and'supportingtrough is al- Ways substantially horizontal and never rocked or tilted or inverted. This advantage is attained by the construction already described in connection with Figures 6 and 7, and the maintenance of the horizontal position ofthe assembll'es is' due to the-fact that all of the sets of rocker arm" mechanisms (two ofwhich are shown) the bars 56 and 51, as wellas the rock arms 6t and 65, associated with each mandrel assembly are of substantially identical dimen- Due to the. fact that the entire assembly is bodily shifted from one position to the other,

it, is. necessary positively to lock each of the mandrel: rod assemblies. to the frame to anchor .the mandrel rodsv when the parts are in the drawing position. In addition to locking positively the mechanism as a whole, it'i'sfurther semblies are shown in" Figure 5 with the upper to the proper position in the die.

supporting tubes 3'4- in which the mandrel rods are contained are supportedgin blocks N13 (Figure; 5-) to maintain them in alignment with the dieblock and a short distance above the'bottom of. the trough 35. Lubricant may be supplied to the interior of the tubes 34 as hereafter described. The bottom portion of each trough 35 terminates at H0 (Figure 5") and two side flanges 2 (Figure 9) continue and terminate at across bar. H4v atthat end of each mandrel red assembly remote from the dies 25..

Each of the three mandrel rod mechanisms mounted in each trough 35 and its flanges H2 comprises the tube 34 in which is the hollow orxsolidima-ndrel .rod 30, one end of which is secured at HB to a sleeve H8 slidably received in. a: larger sleeve I20. This latter sleeve is threaded in a cross block |-22 disposed between the extending portions of the trough flanges H2 and thesleeve I20 is locked infadju'stedaposition by a locking nut I24. vThe mandrel rod 3d and the: sleeve :8 which is slidable in-the sleeve |.20-- arelimited in axial movement in one direction by a pair. of locking'nuts I2=6 threaded on the sleeve H8 and adapted t'oxseat against the end of the sleeve I20 as shown. The nuts normally are held against the outer sleeveil 2fl by a compression spring I 30 that surrounds sleeve H8.- and at one end bearsagainst outer sleeve I20 at I32 (Figure 8) and at the: other end againsta nut 134 adjustably mounted on the sleeve H8.

The mechanism just described permits movement of themandrel rod- 30 and'i't's: plug32' with respect to the trough and toward and away fromthe die 25 (Figure 2) The spring normally urges the plug 32 as close to the die as the nut IZB-and sleeve [20 will permit. When the pointed end of the tubeto be drawnis pushed into the die, the plug can only advance as far as the inside diameter of the tube point permits, and frequently the plug cannot advance When the drawing commences, the point advances through the die and the compressive force of the: spring pushes the plug and rodforward into the proper position in relation to thedie; The degree of spring compression and the po'sition'of the-mandrel rod 30 with respect to the cross block I22 are governed respectively by the adjustment of the nut I34 and the position of sleeve IZU i'n thecross block I22.

During the operation of drawing a tube through the die 25 and across mandrelS-E', it is desirable to supply lubricant at the mandrelon the inside of the tube. In the machine of the present invention this is accomplished by making the mandrel rods 30hol1ow for their entire length and forcing lubricant through from the'anchored end and the sleeve H8. For this reason the sleeves and rods are provided with fluid tight connections at H6 where they are joined. At the other end of each sleeve H8 is a connection 135- to a flexible hose 136a, I362) or 1360. Each of the hoses for each of thethree sleeves H8 is connected as shown in Figure 9 to the hollow cross block I22 from which they are supplied with lubricant; the connections are arranged as shown sothat each hose may-have a loop of as large a radius as possible in order that the hoses may not be bent too sharply as adjustments are madebetween the respective sleeves I and the cross block I22. Lubricant under pressure-is supplied to the hollow interior of the cross block by a fitting I which communicates with connections I4Ia, Hill), and [M0 where the hoses I36a, I36b and I360, respectively, are connected.

In order to lock each mandrel rod'assembly including its associated trough 35 against lateral movement relative to the frame during the drawing operation, the follower mechanism shown in Figures 5, 8 and 9 is provided. This comprises an air cylinder I secured at each of its'ends to brackets I41 and I48 which in turn are slidably mounted on guide'rods I50 and I5I. These rods are each secured at one end to the cross member H4 and at the other end to a cross bar I52 (Figure 5) welded on the undersideof the extension members H2. The cylinder has mounted within it a piston I53 that is secured to a piston rod I54 (Figures'5 and 8) rigidly anchored at one end to the cross member II4.

Fluid under pressure is admitted to either end of the cylinder through connections I56 or I51 so that reaction of the fluid on the pistonand the cylinder end walls will move the latter back and forth on the guide rods I50 and. I5I. The

cylinder is provided at its left hand end- (Figure,

5) with a packing gland I59 and at its right hand end with a locking plunger I60. The locking plunger is rigidly secured to the cylinder end and is adapted to be seated within an opening or. recess I62 of a block I65 that is supported and secured on top of the end frame of the frame that supports the mandrel rod. assemblies. The end frame, the block I65 and the I-beam 53 are all rigidly welded together.

When a mandrel rod assembly is in the tube drawing position 23 (Figure 1), air is admitted at I51 to the cylinder I45 thereby to move the plunger I toward the right (Figure 5) and into the recess I62. A block I10, rigidly secured to the under side of the trough 35, lies in lateral abutment with the right hand end of the block I and prevents the fluid pressure against the cylinder from moving the supporting trough 35 to the left (Figure 5).

Lubricant is supplied to the inside of the mandrel supporting tubes 34 and to the inside of the hollow mandrel rods 30 by a lubricating system shown in Figure 4 and that is electrically interlocked with the movement of the mandrel assemblies so that lubricant is supplied only to the assembly that is Fittings I12 are provided on the underside of each trough to communicate with the interior of each tube 34. To each fitting is secured a two way valve I14 and to each valve is fastened a section offiexible hose I15a or I15b. These hoses from each mandrel rod'assembly are connected at I to different ports on the outlet side of a four-way solenoid operated valve I82. The insides of the mandrel rods 30 are supplied through two way valves I84 with lubricant in drawing position.'

assembly in drawing position.

position. When an assembly is moved from the drawing position to the loading position the supply of lubricant to it is automatically cut off. A return pipe I9I leads from the valve back to the central supply.

Air. pressure is used to operate the cylinder 89 by which the shafts 15 and 80 are rotated and also to operate the cylinders I45 of each mandrel rod assembly. Air under pressure is admited through a regulator valve 200 to a four-way solenoid operated valve 202. Air passes from the valve to lines 205a, 205b and 206a, 20Gb that lead to the respective supply fittings I56 and I51 of each of the cylinders I45. At the desired time, air is admitted through the valve 202 'to fitting I51 of the particular cylinder I45 of that Imandrel rod assembly that is in drawing position and thereby advances the mandrel rods toward the die stand projecting the pointed ends of the tubes loaded thereon through the dies and moves its locking plunger into the recess I62. An interlock is provided so that at this time lubricant begins to be supplied to the hollow mandrel rods 30 and the tubes 34 of the When it is desired to shift the mandrel rod assemblies, air is admitted at the fitting I56 of the lowermost cylinder to move themandrel rods away from the die stand and withdraw the locking plunger from the recess I62. Air is then supplied to the cylinder 89 to rotate the shafts 15 and 60 to interchange the mandrel rod assemblies from the positions that they previously occupied. I

A modified form of mandrel rod assembly and its supporting mechanism is shown in Figure 10. In this construction. the troughs supporting the mandrel rods are not maintained quite horizontal, as is the case with the mechanism shown in Figures 6 and '7, although they can be described as always substantially horizontal. This modified form of construction may be mounted on a frame like that built around beam 53 (Figure 5) although in the present instance, it is desirable to employ a modified form of frame construction in which a beam 2I0 is used with its web lying horizontal. This beam is supported on frame members 2II in the form of modified structural shapes with a web 2 I2 and side plates 2I4.

The mandrel rod assemblies are shifted between the loading position 22 and the drawing position 23 by two or more rock arm mechanisms spaced apart along the beam 2I0,.and connected to a shaft 2I5 extending between and mounted in hearings in frame members 2II.

Secured to the shaft for rotation through an arc of approximately are two rock arms 2I6. At their ends each rock arm makes pivotal connection at 220 with supporting rod members 22I and 222. At their upper ends these rod members support troughs 225 in which are mounted the usual mandrel rods 30 and their surrounding tubes. At their lower ends, the rods 22I and 222 arereceived in sliding bearings 220 that are in turn pivotally mounted at 229 on adjacent frame members 2I I.

It will be apparent from the construction described that as the rock arms 2I6 are rotated about the axis of the shaft 2 I5, the rods 22I and the mandrel rod assembly supported by them will be moved through the dotted line position of Figure 10 and the rods 22I will slide correspondingly in the pivotal bearings 228. Further movement of the rock arms. 2I6 will ultimately bring the left hand assembly of rods 22I down r into the position occupied by the right hand will have been moved up until its mandrel rods are in the upper or loading position. The two mandrel rod assemblies are moved far enough outwardly by rock arms 2l6 to pass each other as they move from one to the other position.

The rock arms 2 I6 are rotated by a piston and cylinder mechanism 230 corresponding generally to the cylinder 89 described in connection with Figure 11. The cylinder 230 is pivotally mounted at one end at 232 to a bracket rigid with a frame 2| I. At its other end the cylinder is provided with a packing gland through which passes a piston rod whose piston is within the cylinder and whose free end is connected at 235 to one of the rock arms 2|6. Admission of fluid under pressure into the cylinder 23!] will cause relative movement between it and its piston to rotate the rock arms 2| 6 about the axis of the shaft 2| 5 in the same manner as the mechanisms in Figures 6 and 7 are moved. Since the two rock arms 216 are connected through the shaft 2| 5 for simultaneous movement only one cylinder mechanism 230 is required.

It will be seen that the mandrel rod assemblies are tilted only slightly in their travel from one position to the other, substantially the extreme amount of tilt being shown in the broken line position in Figure 10. Thus, with this arrangement, just as in the first modification, lubricant can be retained in the supporting trough, and if desired open troughs may be employed instead of the tubes 34.

Reference is hereby made to my co-pending application Serial No. 247,985 filed September 24, 1951 which contains claims directed to the modified form of the invention just described.

From the foregoing description of two preferred forms of my invention, it will be evident that I have provided an efficient type of draw bench that can be operated to draw one or more tubes simultaneously from supporting mandrel rods. The mandrel rods are provided in two independent assemblies and are horizontal in both the loading and drawing positions and may be shifted between these positions without being rocked, tilted or inverted. The mandrel rod assemblies are supported and shifted by a plurality of identical mechanisms, and this results in considerable economy of manufacture because many duplicate parts may be used. With the draw bench of the present invention, it is possible simultaneously to look a mandrel rod assembly immovably with respect to the die and at the same time advance the mandrels on the mandrel rods of the locked assembly to drawing positions adjacent the dies.

Those skilled in the art will appreciate that various changes and modifications may be made in the apparatus described herein without departing from the spirit and scope of my invention. Therefore, it is to be understood that my patent is not limited to the preferred forms described in detail herein or in any manner other than by the scope of the appended claims.

I claim:

1. In a draw bench including a die stand, a plurality of drawing dies in said die stand with their axes horizontal and parallel to each other, and a back bench, the combination of two mandrel rod assemblies each including as many mandrel rods as there are dies in said die stand, the mandrel rods of each assembly lying horizontal and parallel to each other; a mandrel at one end of each mandrel rod; supporting means for each mandrel rod assembly transmitting thereto, but without producing therein substantial rotation about its axis, transverse movement between a tube loading position and a tube drawing position, said means including elements to retain the mandrel rods of each assembly horizontal and in the same relative position with respect to each other during movement from one to the other position; and a follower acting in unison on the mandrel rods of the assembly in drawing position simultaneously to locate said mandrels in cooperative drawing relation to said dies respectively and to lock said assembly in drawing position.

2. A draw bench as in claim 1, said supporting and retaining means including the combination of a supporting frame; two horizontally extending vertically aligned shafts rotatably mounted in said frame in spaced relation to each other; two rock arms, one mounted on each of said shafts, each of said rock arms having opposed arms extending outwardly on each side of its shaft; two vertically standing bars carrying the mandrel rod assemblies, one at each side of said shafts, each pivotally secured to each of the ends of said rock arms at its side of the shafts; and means common to the two shafts to rotate both of said shafts simultaneously.

3. A mandrel and manipulating mechanism including a frame, two mandrel rod assemblies each including a horizontally disposed mandrel rod with a mandrel at one end thereof; supporting means for each mandrel rod assembly transmitting thereto, but without produ therein substantial rotation about its axis, transverse movement between a tube loading position and an operating position, said means including elements to retain the mandrel rod of each assembly horizontal during movement from one to the other position; means acting on the mandrel rod of the assembly that is in operating position and movable'longitudinally thereof to shift said mandrel rod longitudinally to place said mandrel in operative location; means movable with said longitudinally moving means and by said movement locking said mandrel rod assembly in operative position; and a power system imposing on said supporting means relative movement in two laterally spaced but mutually similar loci extending uniformly from end to end along said back bench.

DONALD V. S'IROCK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

